Probably a linked variable or two here. Thinking aloud: 1. Higher income. Like, substantially higher income. 2. Later marriage. People don't tend to get marrie

Probably a linked variable or two here. Thinking aloud: 1. Higher income. Like, substantially higher income. 2. Later marriage. People don't tend to get married in college, and I expect to find that people who get married early have higher divorce rates than average.